1. Field of the Invention
The present invention relates to a telecommunications network and more particularly to a method of, and a system for, improving fraud detection within a telecommunications network.
2. Description of Related Art
Rule-based fraud detection systems attempt to detect fraudulent usage by comparing details of individual calls over the telecommunications network with a series of one or more predefined rules. If a particular usage of the network to be referred to throughout this specification as a "call record") triggers one or more of the predefined rules, an alarm is generated, enabling a human operator to take the necessary action. While such systems have had some success in combating fraud, they tend to be labor intensive since the rules tend to be specific to one particular area, and need to be set up and continually maintained by skilled personnel. One set of rules, for example, needs to be set up and maintained to deal with potential mobile telephone fraud, another set for calling card and credit card fraud, another set for PSTN fraud, and so on. A further serious drawback is that in time fraudsters get to know (deduce) the rules and/or thresholds that are being applied, and can modify their behavior accordingly (e.g., "surfing under the thresholds"). For example, if a fraudster knows that he will be detected if he makes a fraudulent international telephone call to a particular number lasting more than thirty minutes, he is likely to start ensuring that all of his calls last for less than that. Conventional systems have difficulty in coping with this, since the rules need to be changed by experienced personnel who are frequently in possession of insufficient information to determine what the effect on the system would be if they were for example to set a reduced time limit of say twenty minutes.